kitna chala ha?
have u tried with different companies petrol?
also use havoline ..
filter original lagaya karo,,
plug kaisa ha? kis cmpany ka ha? kitna chala hay? if it has done 15000km then change it with genuine ngk c7hsa
lube ur chain
check air pressure in tyre,
clean and readjust ur carb,, clean its jets with coompressed air,, jo moun sa phonk mar ka saaf kartha hain that not always works, or use really thin wires to clean the jets..